The whole thing. I especially want to know how you made the wings detachable.

Well, in a nut shell here is what I did. Firstly, I printed off a template for the butterfly wing to the size I wanted (you can easily find it online). I placed it on my black craft foam and cut out the wing, using the template as guidelines (this step might need some practice to get right). I spent quite a bit of time cutting the wings with scissors afterward to get it to look exactly how I wanted after initially cutting out the big pieces. Then I varnished and decorated it and attached a transparent sheet in the color I wanted to the back of the wing with glue.

After making two wings this way, I got to work on the base. You can make your own base with foam, cover it with craft foam and then attach the wings to the base. With that specific pair of headphones though, what I did was cut a hole in the padding (on the inside of the speaker part) big enough to slide the wing in between the plastic part and foam padding. To ensure that the wing would not fall off, I used velcro! That way, I could easily remove the wing and not worry about losing it!

Sounds pretty simple but it is really time consuming when you're as OCD as I am about having perfect wings